The frequency response is not any better then the $199.00 Radio Shack Accurian HD radio, but the Radiosophy costs $269.00.
freq. response 150 Hz to 20 kHz +/-3dB
Since most people can't hear above 15kHz and many people much less then that, I'd rather have better bass response then added super-sonic highs. Loud CD/Radio listening, rock concerts, gun use, industrial noises, and many other things cause high frequency hearing loss.
Other analog stereo FM radios have more useful frequency response, and cost less.
Most people are happy with the broadcast range and audio quality of FM, and the variety offered by satellite radio, iPods, MP3 players, the higher bitrate internet stations, CDs, and other audio sources, so there is little interest or benefit to this (and similar) HD radios.